Bacteria

Mycobacterium leprae

Typical acid fast bacilli, single in parallel bundles or in globular masses, are regularly found in scraping from skin or mucus membrane (particularly the nasal sputum) in lepromatous leprosy.
The bacilli are often found within the endothelial cells of blood vessels or mono nuclear cells.
The organisms have not been grown on artificial media.
When from human leprosy (ground tissue nasal scraping) is inoculated into foot pads of mice local granulomatous lesion developed with limited multiplication of bacilli.
Inoculated armadillos develop extensive lepromatous leprosy, and armadillos naturally infected with leprosy have been found in TEXAS & MEXICO.
M.leprea from armadillo or human tissue contains a unique O-diphenol oxidase perhaps an enzyme characteristic of leprosy bacilli.
Clinical finding:
The onset of leprosy is insidious. The lesion involves the cooler tissue of the body: skin, superficial nerves, nose, pharynx, larynx, eyes and testicles.
The skin lesions may occur as pale, anesthetic macular lesion 1-10 co in diameter; diffuse or discrete erythematous, infiltrated nodules 1-5 cm in diameter; or diffuse skin infiltration.
Neurologic disturbances are manifested by nerve infiltration and thickening with resultant anesthesia neuritis, paresthesia tropic ulcers, and bone resorption and shortening of digits. The disfigurement due to the skin infiltration and nerve involvement in untreated cases may be extreme.
Systemic manifestation of :-
Anemia
Lymphadenopathy
Eye involvement ( common )
amyloidosis

The disease is divided into 2 major types (with several intermediate stages):

lepromatous type
tuberculoid type
1- course is progressive & malign with
Nodular skin lesion

1- course is benign & non progressive with macular skin lesion

2- slow symmetric nerve involvement
2- severe Asymmetric nerve involvement of sudden onset
3- abundant acid –fast bacilli in the skin lesion
3- few bacilli present in the skin lesion
4- (-ve ) lepromin skin test
4- (+ve ) lepromin skin test
5- in lepromatous leprosy cell mediated immunity is markedly deficient & the skin is infiltrated with suppressor T-cells
5-in tuberculoid leprosy cell mediated immunity is intact & the skin is infiltrated with helper T-cells

DIAGNOSIS :-

Scraping with a scalpel blade from the skin or nasal mucosa or from a biopsy ear lobe skin are smeared on a slide and stained by Ziehl-neelzon technique
Biopsy of the skin or of thickened nerve gives a typical histologic picture.
No serologic tests are of value
Nontreponemal serologic tests for syphilis frequently yield false – positive result in leprosy.


Treatment :- للأطلاع
Sulfones (dapsone), or Clofazimine + rifampin (in sulfones resis. Leprosy)
For many months
Epidemiology
Transmission of leprosy is most likely to occur when small children are exposed for prolong periods of heavy shedder of bacilli.
Nasal secretion is the most likely infectious material for family contact.
The incubation period is probably 2-10 years.
Without prophylaxis about 10% of exposed children may acquire the disease.
Treatment tends to reduce and abolish the infectivity of patient.
Naturally armadillos have been found in TEXAS & MEXICO, but probably play no rule in transmission of leprosy to humans.
Prevention and control :-
Identification and treatment of patient with leprosy is the key to control. Children of presumably contagious parent are given chemoprophylaxis drugs until treatment of the parent has made them noninfectious if any member of domestic group has lepramatous leprosy. such prophylaxis is required for the children in the group
Experimental BCG vaccination an M.leprae vaccine are also being explored for family contact & possibly for community contact in endemic areas.